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Multiple Chemical Sensitivity (MCS) - what you should know

Learn about MCS and its causes, symptoms, triggers, and more.

Table of Contents

What is Multiple Chemical Sensitivity?

Multiple Chemical Sensitivity (MCS) is a term used to describe a class of conditions that some individuals develop after they are exposed to certain chemicals. The variety of symptoms individuals experience depends upon the type and intensity of the chemical exposure.

Symptoms can range from those that produce only mild discomfort, such as a headache to more severe reactions such as asthma an attack.

Although some foods, molds, and natural allergens have been implicated in the development of MCS, chemical exposure is suspected to be the leading cause of the disorder.

One of the notable features of MCS is that sensitivity to chemicals can develop even at exposure levels that are generally considered safe for the average person.

How do I know if I have MCS?

Exposure to a variety of substances can prompt symptoms in a number of people in the general population. However, such reactions do not necessarily mean that you have MCS. People who suffer from MCS experience a variety of adverse health effects. Common symptoms include but are not limited to:

  • Headaches
  • Fatigue or general malaise
  • Confusion or Disorientation
  • Problems concentrating
  • Short-term memory problems
  • Dizziness
  • Fainting spells
  • Flu-like symptoms
  • Asthma or other breathing problems
  • Muscle and joint pain and weakness
  • Irregular or rapid heartbeat
  • Increased sensitivity to odor
  • Rashes
  • Gastro­ intestinal problems
  • Depression/Irritability
  • Breathing problems

Who gets MCS?

It is not normal to regularly experience these kinds of symptoms.  If you suffer from these health problems on a regular basis you should talk with your doctor; you may want to ask for a referral to a doctor who specializes in occupational and/or environmental medicine.

Although people of all ages, races and economic backgrounds may develop MCS, those identified as most at risk for developing MCS include people who:

  • Work in occupations that expose them to industrial chemicals
  • Work in buildings with serious indoor air quality problems
  • Are exposed to hazardous waste, pesticides, and other environmental contamination
  • Are exposed to chemicals from remodeling activities in their home or office

What causes MCS?

Although many chemicals, as well as certain foods, molds and natural allergens, have been implicated in the development of MCS there is no one universally accepted mechanism to explain what causes the condition to develop.  An individual may develop MCS after one substantial chemical exposure or after several lower-level exposures to substances such as pesticides, solvents or cleaning solutions. It has been suggested that this initiation or “induction” stage is followed by “triggering” of symptoms by everyday, levels of chemicals and certain foods that they had previously tolerated.

Is MCS related to poor indoor air quality?

It is generally accepted that indoor air quality is likely to play a major role in both the development (induction) and chronic reoccurrence (triggering) of MCS symptoms. Individuals in offices where new rugs have not sufficiently off-gassed prior to occupancy have been implicated in MCS, as have remodeling activities. The chemical off-gassing from substances such as perfumes, tobacco smoke, copiers, glues, newspapers, and leather also have been reported to act as triggering agents.

Substances reported to act as Initiators and Triggers of MCS

Although a variety of chemicals and chemical combinations may serve as initiators and/or triggers of MCS, certain substances have been reported to play a more significant role than others.  This is especially true with regard to pesticides and the onset (initiation) of MCS.  Substances that trigger MCS symptoms vary from person to person. These are only partial lists.

Suspected Initiators

  • Pesticides
  • Some industrial solvents
  • Volatile organic compounds (VOCs)
  • New carpeting
  • Office/building renovations
  • Anesthesia
  • Diesel exhaust

Suspected Triggers    

  • Nail polish/remover
  • Fragrances
  • Tobacco smoke
  • Insecticides
  • Dry-cleaned clothing
  • Alcohol
  • Hair care products
  • Markers
  • Off-gassing of paint
  • Caffeinated products
  • Latex
  • Some cleaning agents
  • Gasoline
  • Off-gassing of office products

There are many diagnostic techniques that a physician can use to determine if a person suffers from MCS.

How is MCS diagnosed?

Physicians typically diagnose MCS by taking a health history, performing a physical examination, and investigating whether symptoms come and go in response to chemical exposures. To determine if an individual’s symptoms are the results of chemical exposures in the work or home environment, an occupational/environmental health specialist may ask questions to determine whether symptoms are more prevalent at work versus the home environment.

Can any physician diagnose and treat MCS?

While many healthcare providers may see patients with these types of symptoms, generally, physicians who focus in occupational/environmental medicine are in the best position to recognize and treat individuals with MCS.  If you suspect that you suffer from MCS you may want to take this brochure or other related information with you when you see your doctor.

What can an individual with MCS do to reduce the likelihood of a symptomatic response?

People with MCS report that avoiding exposures to chemicals, foods and drugs that trigger symptoms is an important first step. Since pollutants in confined spaces (e.g., indoors) are thought to be a major source of both initiating and triggering exposures, maintaining optimal indoor air quality is important.  In addition, a variety of treatment options including nutritional supplementation and other therapies have been reported to be helpful.  Treatment options should be discussed with a physician who is knowledgeable about MCS to decide which may be appropriate. You may want to bring this brochure with you when you consult a health care provider.

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